Certain industries, such as the chemical and petroleum industries generate waste gases that need to be controlled. One means of disposing of such waste gases is to burn them in a technique commonly referred to as flaring. Measurement of the constituent gases present in flare vent gas is of importance in assessing the operation of a flare with respect to conformance with environmental regulations. However, there is no single practical method of measuring the components of a gas mixture that can identify all of the potential constituents of flare vent gas of interest in near real time. For example, homonuclear diatomic gas species, such as hydrogen, nitrogen and chlorine, cannot be detected using spectroscopic methods that rely on transitions between states in molecules having a permanent electrical dipole moment. Moreover, commonly used methods that do not rely on molecular dipole transitions such as gas chromatography, are not suited to rapidly changing gas compositions. Therefore systems and methods that address the measurement of flare vent constituent gases are of interest.